7mm Rem Mag | 168gr Accubond Long Range | Reloder-25

[MAGA]

Hello everyone. I have been browsering these fine forums for many years, but today I thought I would take the plunge, register, and make a post! I'm fairly new to reloading, but I'm pretty confidant in my understanding of all the logic behind different techniques, tests, etc. Either way, I'll get to my question(s).

Rifle: Sako A7
Barrel: 24.4"
Caliber: 7mm Remington Magnum
Bullet: Nosler 168gr Accubond Long Range (ablr)
Brass: Hornady
Powder: Reloder-25

Let me just say that this Sako A7 is a shooter. I've used a variety of factory ammo and it has achieved 0.5" groups @ 100 yards on numerous occasions. It is a tack driver and as long as I do my part, it'll do the rest. Note: I am not an expert shooter by any means, but I do consider myself a lucky shooter (could go more into that).

As I'm sure most of you know, Sako, and its little brother Tikka, have a detachable magazine, which consequently will limits the COAL of round/cartridge, assuming the shooter wants to use the detachable magazine as opposed to just manually feeding a round in at a time. So for purposes of this load development, I'll be using the magazine.

I did some testing to see what my max COAL for this rifle using Hornady's little OAL guage tool.
The max COAL for this rifle using the above bullet is 3.445" when measuring the tip of bullet to the base of the brass using a EZCal caliper. Where the rifling/lands actually make contact with the bullet, I'm not certain at this time (can do more testing, just haven't yet.)

The max length for inside the magazine is 3.345".

So for the above bullet combo:
max chamber/rifle COAL: 3.445"
max magazine COAL: 3.345"

for a difference of 0.100"

Now with the parameters established, let's take a look at Nosler's load data for the above bullet-caliber combo:

Take note of the Tested O.A.C.L. of the tested loads.
3.250"
That is roughly a 0.195" 'jump' to the rifling/lands. (correct me if I'm wrong).


Now my questions are,

Does anyone have experience loading 7mm Rem Mag rounds with 168gr Nosler Accubond Long Range? What has your experience been with them?

For load testing/development, should I start with the short Nosler COAL or start with my magazines max COAL?

What are the advantages or disadvantages of seating the bullet to max magazine COAL vs. what Nosler is offering here?

How does the powder change the dynamics of the round/load when the bullet is seated at differing depths?

Lastly, does anyone have any experience with 7mm Rem Mag and Reloder-25?

Thanks! Hopefully this isn't too long winded, just wanted to be as accurate as possible.

 

[coyotezapper]

I shoot the 168 LRAB in a 7SAUM and it is a very accurate bullet. I have tested it in wet phone books but that is it. From what I can tell by these tests I expect it to perform very good on game.

Don't worry about COAL or jump numbers. Start your testing at magazine length and then seat deeper to tune if needed. My 7SAUM shoots 1" .010" in the lands and in the "ones" at .030" jump. There is no one absolute in seating depth.

Seating bullets deeper will decrease case capacity and increase pressures / velocities, but as long as you stay within recommended load specs you will be fine. For example if you use Nosler data then use Nosler brass. Case capacity differences between manufactures can make a big difference in pressures. Use a chrono if possible and don't exceed max velocities listed.

As far as your powder choice I would recommend switching to RL26 or H4831. RL26 is one of the most linear powders I have ever worked with and gives a little more velocity that H4831. RL26 is ideal for this case.

 

[MAGA]

Thank you for the reply.
I'll start with the max COAL that fits the magazine.

Should I still follow the powder charge guide from Nosler even though the COAL is longer than the tested load?

 

[coyotezapper]

Follow their powder charge recommendations using your OAL with their BRASS and you will be fine. Use chrono if possible and stop at max velocity listed. The end powder charge may be different but velocity will be the key to determining max pressure.

 

[trent.g]

Hi guys. Been a lurker on these forums for a while as well. I realize this is an old thread, but wondering if anyone had an update on seating depth. I too bought a Sako A7 in 7 Rem Mag in Dec, 2018. (It's the Roughtech model with the aluminum bedded stock and heavy sporter fluted barrel.) Couldn't get it to shoot worth a ****, sent it away to Stoeger Canada for warranty inspection and they said it had excessive headspace. They replaced it and I've been fighting with the replacement gun since April. Some days it shoots ok, some days it doubles the groups for no apparent reason when I re-test the recipe. It's like every time I zone in on what looks like a sweet spot it won't repeat the results or improve on them. Mostly max mag length so far trying to find the best powder charges. I started changing the seating depth drastically in the last week and got a couple back to back bug hole groups that I need to re-test to confirm they aren't a fluke.

Both tested max COAL for the gun were 3.430". Max mag is also 3.33" on my Sako.

-Hornady ELDX 162
Sako brass
69.3gr H1000
CCI BR2
3.29" COAL - about 0.140" jump!
1-4 in a bug hole + 5th shot failure to fire. Probably mis-handled the primer?

I haven't chased variations on the ELDX as thouroughly as the ABLR. I got more consistent results around MOA with H1000 than H4831, and pretty much dropped from max mag length 3.33" to 3.29" on a whim to try out. Needless to say, I was shocked at the group it produced last night, and am skeptical on this one.

-Nosler ABLR 168
Nosler brass
65.3gr H4831sc (No pressure signs till 65.6gr on a warm day...)
CCI BR2
3.295" COAL - about 0.135" jump!
1-4 in a bug hole + 5th shot flier measuring 0.92"

H4831 initially tested better than H1000 overall for this bullet. I had a really hard time picking what powder charge to focus in on because nothing was getting MOA. I played a little with 3.325", 3.32", and 3.31" without anything notable. Also tested 65.3gr in all lenghts. Velocities seemed a little more consistent with the extra 0.1gr powder. but then I managed to get MOA with 65.2gr H4831 @ 3.30". Cold shot in the group high, and the subsequent 4 shots within a 1/2". Re-testing that same recipe netted a 1-1/2" shotgun pattern... 65.3gr @ 3.295" may or may not be the solution for me, but I have to re-test. The load variations around this group were not even close at 3.290" or 3.30" COAL, so I have trouble believing my results with 65.3gr @ 3.295" will be consistent and repeatable. I'm also running about 150fps slower than Nosler's reload data, but that's not the end of the world.

Has anyone else had good results with such a huge jump to the lands? I really want to make this bullet work in this gun, but I'm just about ready to cut my losses on it and buy a Browning or something. Also tested regular Accubonds in 140/160, and ABLR in 150 all at max mag length with really inconsistent results.

 

[coyotezapper]

Hi guys. Been a lurker on these forums for a while as well. I realize this is an old thread, but wondering if anyone had an update on seating depth. I too bought a Sako A7 in 7 Rem Mag in Dec, 2018. (It's the Roughtech model with the aluminum bedded stock and heavy sporter fluted barrel.) Couldn't get it to shoot worth a *Rule 4 Violation*, sent it away to Stoeger Canada for warranty inspection and they said it had excessive headspace. They replaced it and I've been fighting with the replacement gun since April. Some days it shoots ok, some days it doubles the groups for no apparent reason when I re-test the recipe. It's like every time I zone in on what looks like a sweet spot it won't repeat the results or improve on them. Mostly max mag length so far trying to find the best powder charges. I started changing the seating depth drastically in the last week and got a couple back to back bug hole groups that I need to re-test to confirm they aren't a fluke.

Both tested max COAL for the gun were 3.430". Max mag is also 3.33" on my Sako.

-Hornady ELDX 162
Sako brass
69.3gr H1000
CCI BR2
3.29" COAL - about 0.140" jump!
1-4 in a bug hole + 5th shot failure to fire. Probably mis-handled the primer?

I haven't chased variations on the ELDX as thouroughly as the ABLR. I got more consistent results around MOA with H1000 than H4831, and pretty much dropped from max mag length 3.33" to 3.29" on a whim to try out. Needless to say, I was shocked at the group it produced last night, and am skeptical on this one.

-Nosler ABLR 168
Nosler brass
65.3gr H4831sc (No pressure signs till 65.6gr on a warm day...)
CCI BR2
3.295" COAL - about 0.135" jump!
1-4 in a bug hole + 5th shot flier measuring 0.92"

H4831 initially tested better than H1000 overall for this bullet. I had a really hard time picking what powder charge to focus in on because nothing was getting MOA. I played a little with 3.325", 3.32", and 3.31" without anything notable. Also tested 65.3gr in all lenghts. Velocities seemed a little more consistent with the extra 0.1gr powder. but then I managed to get MOA with 65.2gr H4831 @ 3.30". Cold shot in the group high, and the subsequent 4 shots within a 1/2". Re-testing that same recipe netted a 1-1/2" shotgun pattern... 65.3gr @ 3.295" may or may not be the solution for me, but I have to re-test. The load variations around this group were not even close at 3.290" or 3.30" COAL, so I have trouble believing my results with 65.3gr @ 3.295" will be consistent and repeatable. I'm also running about 150fps slower than Nosler's reload data, but that's not the end of the world.

Has anyone else had good results with such a huge jump to the lands? I really want to make this bullet work in this gun, but I'm just about ready to cut my losses on it and buy a Browning or something. Also tested regular Accubonds in 140/160, and ABLR in 150 all at max mag length with really inconsistent results.

Ideal seating depth will differ from rifle to rifle. It is impossible to say one seating depth will work in all rifles. Just test them. There is no short cuts in load development.

 

[trent.g]

Ideal seating depth will differ from rifle to rifle. It is impossible to say one seating depth will work in all rifles. Just test them. There is no short cuts in load development.

Yeah, I'm thinking it might just be a really crappy experience with Sako. I'm at about 400 or maybe even 500 shots searching for anything better than barely MOA and I've had only a handful of groups that looked good, but didn't perform when re-tested. If I keep it up, I'm going to kill the barrel before finding a load that works well and works consistently. I actually packed up this warranty replacement gun and sent it back to Stoeger last month because I couldn't get anything to run the way I think it should. Stoeger sent it back saying there's nothing wrong with it. To add salt to the wound, the Sako A7 no longer carries the same 5 shot MOA guarantee that it used to. I'm positive the one I bought (replaced due to headspace issue) was 5 shot MOA, but this one has a little clause in brackets on the first page of the owner's manual that excludes the A7.

 

[trent.g]

I was also just thinking last night about my last results. Is it realistic that a 0.005" difference either way changes from a bug hole with a flier to 1-1/2" groups? The last couple times I tuned sub moa to 3/4" or 1/2" groups, I was making seating depth adjustments of 0.01" at a time.
Hoping the wind dies down so I can re-test after work this evening...

 

[coyotezapper]

I was also just thinking last night about my last results. Is it realistic that a 0.005" difference either way changes from a bug hole with a flier to 1-1/2" groups? The last couple times I tuned sub moa to 3/4" or 1/2" groups, I was making seating depth adjustments of 0.01" at a time.
Hoping the wind dies down so I can re-test after work this evening...

Here are my steps in developing a load. This goes without saying but I'm going to say it anyway, start with a clean barrel. And I mean clean - to the metal, no carbon or copper at all.
1. Pick bullet that will work with my barrels twist rate.
2. Pick powder that will work with selected bullet and cartridge. IMO this is the most important step. Just because a powder or bullet manufacturer says it will work does not make it the ideal powder choice. This step requires a lot of research and most of the internet info is BS. The IDEAL powder will make the rest of the process easy.
3. Load cartridge to magazine length and measure jump to lands. This is for reference only and is used for throat measurements down the road. Save bullet used for this step. I keep mine stored with the dies.
4. Determine starting powder charge and max. Use reloading manual or Quickload to determine these charges. Using some charge from the internet / forum is not wise.
5. With a good bench set up and chrono shoot loads paying attention to velocity. Velocity=pressure. If you exceed book velocity stop. Pressure signs on brass occur long after pressure becomes excessive. If you don't have a chrono then you will have to pay attention to pressure signs on brass and once seen back off a grain or two. This testing can be done at 100 yards with a chrono but if you don't have a chrono its best to do this testing at distance no further than 300 yards is needed. It is important to replicate each rifle bag set up for each shot when shooting at distance. You will be looking for consistent POI and an inconsistent set up will cause your results to be skewed. I shoot three shots of each charge documenting velocity, ES and SD's for each charge. If shooting at distance you will need to log your POI for each shot. If this means walking out and marking each shot then do it. With a good spotter you can do this at the bench and just take a blank target and transfer the POI holes to the blank target.
5a. This is the most important part of load development IMO. What you are looking for here is a velocity flat spot in the powder charge increase. Example would be 60, 60.2 and 60.4 all have the same or close to the same velocity. This is a velocity flat spot. If no chrono then these three charges should show the same POI at 300 yards indicating the same velocity. This can be done at 100 yards but is a lot easier at 300 but at 300 your shooting, wind and bench set up become the weak link and can affect POI. Once velocity flat spot is found load to the middle of it and do seating depth testing. In some cases no seating depth testing is needed but I wouldn't count on this to be the case.

For the 162 ELDX I would recommend H4831 regular or SC - regular has a better fill but either will work. Max safe velocity will be 2950-3000 fps with a 24.4"" bbl.

This thread may help you with evaluating groups at 100 yards if you have no chrono.

http://forum.accurateshooter.com/threads/long-range-load-development-at-100-yards.3814361/

 

[trent.g]

Yes, I've been using a chrono and looking for velocity nodes before sitting down and actually putting groups on paper in those spectrums.
It looks like my ELD-X / H1000 recipe is checking out ok. Not amazing at 3.29", but tightened up at 3.285" with 4 of 5 shots touching on the same horizontal line. 1st shot was a cold bore flier a bit high & left. Not bad at all, but I'll see if I can tune that out by going even shorter.
The ABLR bughole recipe at 3.295" didn't check out. Makes sense to be a fluke between two not so good groups 5 thou on either side. Not sure if I should give up on the bullet or keep testing out to 0.18 jump. For what it's worth, I tossed in 5 regular Accubond 160's in a previously tested powder charge (zero good groups at 3.30" max mag length whatsoever) and they printed in almost a straight vertical line with 0.182" jump. I suppose I could probably go through the ladder testing all over again betweeen 3.25" and 3.28" on everything. Maybe this gun just likes a ginormous jump. For now, I might hunt with the eldx recipe as is, although I'd prefer a bonded bullet.

 

[trent.g]

Wondering if the OP found any definitive results with seating depth? Not sure how to tag MAGA.

My ELD-X load checked out right at MOA with 3.29" COAL putting it 0.14" off the lands.

My ABLR load has vertical stringing with 3-4 shots sub MOA (overall groups over MOA) on both 3.26" (0.17" off) and just under max mag - 3.30" (0.13" off.) Minimal velocity difference between both seating depths, but the ES & SD went up in the middle along with the group size.

If it shoots sub MOA, it's picky and finicky right to the razor's edge. Not the results I was hoping for with a $1400+ rifle from a brand such as Sako... You'd think they could at least hand pick a warranty replacement with exceptional quality to ensure a dissatisfied customer wouldn't continue to be dissatisfied. The jury is still out on when they changed from 5 shot MOA to 3 shot MOA. I've dug up several old ads and product descriptions that indicate the A7 came with the same 5 shot MOA guarantee as the rest of the brand. I contacted Sako through their facebook page to go over top of Stoeger Canada's head.